 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.expressions;

 import org.w3c.dom.Element ;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;

 import org.eclipse.core.expressions.EvaluationResult;
 import org.eclipse.core.expressions.Expression;
 import org.eclipse.core.expressions.ExpressionInfo;
 import org.eclipse.core.expressions.IEvaluationContext;

 public class InstanceofExpression extends Expression {
     /**
      * The seed for the hash code for all instance of expressions.
      */
     private static final int HASH_INITIAL= InstanceofExpression.class.getName().hashCode();

     private String fTypeName;
     
     public InstanceofExpression(IConfigurationElement element) throws CoreException {
         fTypeName= element.getAttribute(ATT_VALUE);
         Expressions.checkAttribute(ATT_VALUE, fTypeName);
     }

     public InstanceofExpression(Element element) throws CoreException {
         fTypeName= element.getAttribute(ATT_VALUE);
         Expressions.checkAttribute(ATT_VALUE, fTypeName.length() > 0 ? fTypeName : null);
     }

     public InstanceofExpression(String typeName) {
         Assert.isNotNull(typeName);
         fTypeName= typeName;
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.jdt.internal.corext.refactoring.participants.Expression#evaluate(java.lang.Object)
      */
     public EvaluationResult evaluate(IEvaluationContext context) {
         Object element= context.getDefaultVariable();
         return EvaluationResult.valueOf(Expressions.isInstanceOf(element, fTypeName));
     }
     
     public void collectExpressionInfo(ExpressionInfo info) {
         info.markDefaultVariableAccessed();
     }

     public boolean equals(final Object object) {
         if (!(object instanceof InstanceofExpression))
             return false;
         
         final InstanceofExpression that= (InstanceofExpression) object;
         return this.fTypeName.equals(that.fTypeName);
     }

     protected int computeHashCode() {
         return HASH_INITIAL * HASH_FACTOR + fTypeName.hashCode();
     }
     
     //---- Debugging ---------------------------------------------------

     /* (non-Javadoc)
      * @see java.lang.Object#toString()
      */
     public String toString() {
         return "<instanceof value=\"" + fTypeName + "\"/>"; //$NON-NLS-1$ //$NON-NLS-2$
 }
 }

